The MAT is easy to make and guarantees an accurate reference point. The pictures are the original prototype and I decided to add a thin piece of AL that sticks up 1/4" between the AL adapter and the angle piece. This allows a positive fore-aft level alignment with the angle. The AL part is 1 1/2" dia round stock about 3" long and center drilled and tapped on the outboard side 1/4" x 28 bolt (allows the angle bar to be adjusted level). The inside is turned to a very close fit inside the axle and the center ridge serves as a stop. Insert the inside part into the axle and mark the exact location of the cotter-pin hole and thru drill the axle part 1/8" to accept the locking pin. The locking pin is steel with a 1/8 shaft with the end tapered to allow easy insertion. The angle is 1 1/2" x 5" (mine is steel since I have a magnetic level) and AL would be fine.